1. Field of the Invention
The present invention relates to displaying images, especially to systems for displaying images by utilizing a horizontal shift register circuit for generating overlapped output signals.
2. Description of the Prior Art
Generally, liquid crystal displays (LCDs) display images utilizing electric fields to control the light transmittance characteristics of liquid crystal material. Accordingly, LCDs include a liquid crystal display panel having liquid crystal cells arranged in a matrix pattern and driving circuits for driving the liquid crystal display panel.
Gate lines and data lines are arranged within the liquid crystal display panel such that their arrangement caused them to cross each other. Liquid crystal cells are arranged at crossings of the gate and data lines. Liquid crystal display panels include pixel electrodes and a common electrode that apply electric fields to each of the liquid crystal cells. Each pixel electrode is connected to a corresponding data line via source or drain terminals of a switching device such as a thin film transistor (TFT). A gate terminal of each of the thin film transistors is connected to a corresponding gate line.
Driving circuits include a gate driver and a data driver. The gate driver sequentially drives the liquid crystal cells on the liquid crystal display panel by sequentially applying a scanning signal to the gate lines. When the gate lines are supplied with the scanning signal, the data driver applies a video signal to respective ones of the data lines. Pictures are displayed by applying an electric field between pixel electrodes of each of the liquid crystal cells in the LCD panel and the common electrode. Electric fields are applied in accordance with inputted video signals.
Shift registers are the most frequently utilized devices to generate the scanning signal. U.S. Pat. No. 6,157,228 discloses a data line driving circuit that includes a shift register. This prior art shift register, compared to the conventional shift register, utilizes less inverters which result in less delay time and a better display quality of the LCD. However, the prior art shift register is implemented using a CMOS configuration. In a COMS manufacturing process more masks are required and therefore the throughput is low.